The Consumer Electronic Bus (CEBus) is a multimedia LAN standard approved for use by the Electronics Industry Association's Consumer Electronics Bus Committee. CEBus provides a standard communication interface to each of six different media. These media include: PLBus (Power Line Bus), TPBus (Twisted-Pair Bus), CXBus (Coaxial Bus), IRBus (Infrared Bus), RFBus (Radio Frequency Bus) and FOBus (Fiber-Optic Bus). CEBus comprises media with data channels and a control channel. The control channel carries commands used to allocate the data channels, as well as short messages. The data channels carry a variety of signals which do not fit within the bandwidth constraints of the control channel. The control channel is digital, whereas the data channels may carry signals of any type.
The CXBus network provides the information necessary to facilitate the exchange of data and control information over the coaxial cable medium within a home. The detailed description of the CXBus network may be found in the "CX Specification, IS-60.3 Coax Physical Layer and Media Specifications", revised Mar. 19, 1992, which is incorporated herein by reference for its teachings on CXBus topologies, media and devices, including "Node Zero" definition. CXBus is also described in O'Brien Jr., "Physical and media specifications of the CXBus", IEEE Transactions on Consumer Electronics, Vol. 37, Number Aug. 3, 1991, which is incorporated by reference herein for its teachings on CXBus networks. A publication by J. Hofmann entitled "The Consumer Electronic Bus: an Integrated Multi-Media LAN for the Home", International Journal of Digital and Analog Communication Systems, Vol. 4, 77-86, (1991), (which is incorporated herein by reference for its teachings on CEBus network architectures) describes issues related to frequency placement of block converted signals.
CXBus network configurations support all anticipated coax connected appliances in the home. The CXBus distribution system includes a collection of coaxial cable pairs that originate at a special node distribution device called "Node Zero" in FIG. 1. This dual cable approach provides sufficient spectrum space for externally generated signals from either a Cable Television (CATV) cable or Off-Air (i.e., from an outside antenna), as well as the video and audio signals generated within the home (e.g., from a video cassette recorder or surveillance cameras). The two cables of this cable pair are described as "external" cable and "internal" cable respectively. The CXBus network may be a single independent network, or the CXBus network may also be interconnected with other CXBus networks or different CEBus media.
The present invention provides a multimedia signal distribution device that implements the Electronics Industry Association (EIA) "Node Zero" standard for a Consumer Electronics Bus (CEBus) signal distribution network that utilizes a unique block frequency conversion circuit to provide an improved wide-bandwidth block frequency conversion of incoming baseband signals not found in the current state of the art. The block conversion circuit of the present invention accomplishes this wide-bandwidth conversion by providing a double frequency shift conversion circuit which permits filtering and amplification of the incoming signals at intermediate (IF) frequencies which are much higher than either the baseband frequencies of the incoming signals or the frequencies of the converted signals output from the device. This double frequency shift IF conversion, filtering and amplification scheme allows the elimination of undesired harmonic frequency sideband components which degrade the output signal in current Node Zero designs. The circuit design of the present invention provides a cost-effective approach to wide-bandwidth signal reception capability for the Node Zero standard through its unique double shift IF conversion, filtering and amplification scheme.
Accordingly, it is an object of the present invention to provide a multimedia signal distribution device that implements the Electronics Industry Association (EIA) "Node Zero" standard for a Consumer Electronics Bus (CEBus) signal distribution network.
It is a further object of the present invention to provide a multimedia "Node Zero" signal distribution device that utilizes a unique block frequency conversion circuit to provide an improved wide-bandwidth block frequency conversion of incoming baseband signals.
It is a further object of the present invention to provide a multimedia "Node Zero" signal distribution device that accomplishes wide-bandwidth frequency conversion by providing a double frequency shift block conversion circuit.
It is a further object of the present invention to provide a double frequency shift block conversion circuit which permits filtering and amplification of the incoming signals at intermediate (IF) frequencies which are much higher than either the baseband frequencies of the incoming signals or the frequencies of the converted output signals.
It is a further object of the present invention to provide a double frequency shift block conversion circuit which allows the elimination of undesired harmonic frequency sideband components which degrade the output signal.
It is a further object of the present invention to provide a multimedia "Node Zero" signal distribution device which provides a cost-effective approach to wide-bandwidth signal reception capability for the Node Zero standard through a unique double shift IF conversion, filtering and amplification scheme.